This invention relates to a novel gypsum board and particularly to a backer board for wet areas, such as behind ceramic tile in bathtub and shower areas
U.S. Pat. No. 4,647,496 discloses a fibrous mat-faced gypsum support surface in the exterior structure of a building with insulating material adhered thereover and an exterior finishing material which may be an acrylic resin based composition or a Portland cement stucco. Woven glass cloth, glass fiber scrim or a glass fiber mesh may be embedded in the exterior finishing material, or between the insulating material and the exterior finishing material as a reinforcing component. The fibrous mat-faced gypsum support surface is preferably a set gypsum core faced with a fibrous mat. The mat can comprise continuous or discrete strands of fibers and be woven or nonwoven, but preferably it is fiber glass filaments oriented in random pattern, bound together with a resin binder, and preferably on both surfaces of the core.
Canadian Pat. No. 993,779 also discloses a gypsum core board with facings formed of woven or unwoven porous glass fiber cover sheets, the woven normally being found more expensive.
U.S. Pat. No. 3,312,585 discloses a gypsum board for use as a backer board for behind ceramic tile in wet areas, formed of a paper covered gypsum core, plus a water impervious film, such as of polyvinyl chloride, covering the front face of the board and at least one longitudinal edge.